Preface (Solar Physics)

The IAU Colloquium No. 143, 'The Sun as a Variable Star: Solar and Stellar Irradiance Variations', was held June 20-25, 1993, at the Clarion House, Boulder, Colorado. The main objective of this colloquium was to review the most recent results on the observations, theoretical interpretations, empirical and physical models of the variations observed in solar and stellar irradiances. A special emphasis of the colloquium was to discuss the results gained on the climatic impact of solar irradiance variability.